柱填充再生纤维素交联凝胶微球的制备及其力学性质的调控

再生纤维素凝胶微球是将纤维素溶液分散于连续相中,并通过一定的固化方式使分散的纤维素溶液液滴发生凝胶转变而制备的凝胶微球材料。纤维素凝胶微球具有比表面积大、亲水性好、非特异性吸附小等特点,可作为吸附剂、生物亲和载体等应用。本文以棉短绒纤维素为原料,采用乳化法（低表面活性剂用量）制备了纤维素凝胶微球。利用XRD、光学显微镜、粒径分析仪、SEM、材料力学测试仪等对纤维素微球的形貌、结构、力学性能进行了表征及测试。考察了乳化剂用量、转速、m（纤维素溶液）:m（液体石蜡）、溶液黏度以及交联剂用量等因素对纤维素微球粒径的影响。结果表明,在纤维素溶液（质量分数4%）为10 g、交联剂用量为300 μL（交联度为3%）、乳化剂用量为0.1 g、液体石蜡用量为30 g、转速为200 r/min,溶液黏度为2474 Pa·s（增黏时间为15 min）的条件下,能制备平均粒径为610 μm的纤维素微球,其中粒径范围在400~800 μm的微球收率为54.93%。另外,本研究尝试了用乙醇水溶液作为凝固浴来调节微球中纤维素链的聚集状态进而改变微球的力学性能。在上述条件制备的纤维素微球,通过无水乙醇处理的纤维素微球能够承受流速为60 mL/min产生的水压,使微球不发生形变,表现出良好的物理性能,有望于应用于血液灌流等填充柱的应用。     

石蜡乳液的制备

以60#全精炼石蜡为原料,乳化剂的加入采用剂在油中加入法制备石蜡乳液;研究了乳化剂种类、乳化温度、乳化时间、去离子水用量、乳化剂的亲水亲油平衡值(HLB)、搅拌速度等因素对石蜡乳液稳定性的影响,结果表明:在乳化剂为TW-80/SP-80,乳化温度85℃、乳化时间30min、w(去离子水)=68%、搅拌速率1 000r/min、HLB=10.006 7的条件下制备出的样品有最佳的乳化效果。     

超临界CO2抗溶剂法制备乙基纤维素微球试验

通过自行设计的超临界CO2微球制备装置,利用乙基纤维素丙酮混合溶液,制备了粒径偏差较小、表面光滑与球形度较好的乙基纤维素微球,采用正交试验讨论了温度、压力、溶液质量浓度、CO2流量对微球粒径与粒径分布的影响,分析了进气与进液方式对试验过程的影响。试验结果表明:改变工艺参数,可在较大范围内调控微球大小,所制微球平均粒径为0.2—2.6μm,粒径偏差为0.07—0.85μm;溶液质量浓度是主要影响因素;不同的汽液接触方式也将影响微球的大小。     

戊二醛交联改性再生纤维素纤维的研究

以氯化1-丁基-3-甲基咪唑离子液体为溶剂对木质纤维素进行溶解并纺丝,得到再生纤维素纤维,再使用戊二醛对再生纤维素纤维进行交联改性,研究其交联改性条件对再生纤维素纤维力学性能的影响。结果表明:经戊二醛交联后,再生纤维素纤维的断裂强度有明显的提高;在戊二醛质量分数为4%,反应温度为50℃,反应时间为30 min的交联条件下,所得再生纤维素纤维的断裂强度为3.2 cN/dtex。     

石蜡乳液制备及性能研究

以高速分散器为乳化设备,58#工业级全精炼石蜡为原料制备了石蜡乳液.考察了乳化剂的组成及其HLB值,乳化剂用量,乳化温度,转速和乳化时间等因素对石蜡乳液性能的影响.结果表明,适宜的乳化工艺条件为:以Span80,K12和助乳化剂A为复配乳化剂,其HLB值为11,乳化剂用量为7％,乳化温度为85℃,转速为2×2 800 r/min,乳化时间为1min.     

反相微乳液交联法制备葡聚糖水凝胶微球的粒径调控

基于天然高分子的水凝胶微球因具有良好的生物相容性,作为生物材料得到了广泛应用。本文采用反相微乳液交联技术制备了一系列葡聚糖水凝胶微球,并探讨了反相微乳液体系中表面活性剂的亲水亲油平衡值(HLB值)、乳化方式、水油相体积比(φ)、水相与表面活性剂的摩尔比(R0)等因素对该葡聚糖水凝胶微球形貌及粒径的影响情况。结果表明:采用环己烷(CYH)/Span 80-Tween 80/醛基化葡聚糖(Dex-CHO)乳液体系制备所得葡聚糖水凝胶微球的粒径在400nm~70μm之间可调;相对于机械搅拌乳化,超声波乳化条件下获得的凝胶微球具有更小的粒径,且当复配乳化剂m(Tween 80)/m(Span 80)=0.10、HLB值=5.27、φ=1/6时,获得的凝胶微球粒径最小(约422nm);葡聚糖凝胶微球的粒径随着R0值的增加呈现增大趋势。该葡聚糖水凝胶微球粒径可控,是一类天然高分子水凝胶,有望作为载体材料应用于生物医学领域。     

再生木浆纤维素的制备及其稳定辛酸/癸酸甘油三酯乳液的性能研究

以高纯木浆板为原料制得再生木浆纤维素(W-RC),并用TEM、FT-IR和XRD对其进行表征,说明W-RC属于典型的纳米基纤维素Ⅱ型颗粒。以辛酸/癸酸甘油三酯(GTCC)为油相,W-RC为乳化剂,制得O/W型Pickering乳液,并通过光学显微镜、荧光显微镜、FE-SEM及流变仪对乳液进行表征。荧光显微镜与FE-SEM的结果显示W-RC吸附在油/水界面并在微球表面及微球间形成三维网状结构。流变学表明W-RC及由其稳定的乳液具有典型的剪切变稀特性。W-RC具有优良的乳化性能,在W-RC质量分数为0.6%、分散相体积分数高达60%时,也能得到稳定的乳液。     

醇酸改性硝化纤维素水乳液的制备研究

采用醇酸树脂相反转乳化法制备了硝化纤维素乳液。分析了反相乳液聚合过程中电导率的变化规律,研究了乳化剂HLB值、乳化剂用量和乳化温度等因素对乳液临界含水量Rf值及其稳定性的影响。     

氧化石蜡乳化研究

以Co/SBA-15为催化剂,52号石蜡为原料,制备氧化石蜡,并考察了乳化温度、乳化时间、乳化剂用量等因素对乳化效果的影响.结果表明,HLB值为9.3的复配型非离子乳化剂具有较好的乳化效果.较适宜的乳化条件为:乳化剂质量分数为7.3%(占总量)、乳化时间55 min、乳化温度75 ℃、乳化用水质量分数为69.96%(占总量).制得的乳液具有稳定性好、保质期长、无毒无味、色泽好等优点.石蜡氧化后乳化性能有很大提高,乳化剂用量减少.     

姜黄素微球制备工艺研究

本实验以L-丙交酯(L-LA)和ε-己内酯(ε-CL)单体开环聚合得到的共聚物(PCLA)为载体,用O/W乳化溶剂挥发法制备姜黄素微球。并采用正交实验法,考察了药物与聚合物质量比、聚乙醇400(PEG400)的质量分数、乳化搅拌转速、温度对微球载药量的影响。通过对工艺的优化,得出较佳的制备条件为药物与聚合物质量比为40 mg/200 mg、PEG400的质量分数为1%、乳化搅拌转速100 r/min、温度为38℃。所制备的载姜黄素PCLA微球圆整,大小分布均匀,粒径分布较窄,平均粒径为(225.52±0.15)μm、载药量(6.15±0.02)%。     

改性纤维素微球的制备及其对Pb2＋吸附性能的研究

利用绿色环保的碱／尿素／水溶剂体系直接制备纤维素溶液共混聚乙烯亚胺（PEI）,然后通过高压静电法制备再生纤维素微球,并与戊二醛交联固定化,制备了复合型吸附材料。借助吸附动力学和吸附等温方程研究了改性纤维素微球对Pb2＋的吸附性能,结果表明改性纤维素微球对Pb2＋具有较好的吸附容量达到9．46mg／g,相比空白微球提高50％以上,并且吸附过程符合准二级动力学方程和Freundlich等温方程。     

蔗渣再生纤维素制备高取代度羧甲基纤维素钠的研究

先以NaOH/H2O2水溶液对蔗渣进行预处理,再用预冷至-12℃的7%NaOH/12%尿素水溶液对预处理蔗渣进行分离,获得结构蓬松的蔗渣再生纤维素。以蔗渣再生纤维素为原料,以氯乙酸钠为醚化剂,在85%乙醇水溶液中,采用一次碱化、二次醚化的工艺,制备了羧基取代度达1.45的羧甲基纤维素钠(CMC)。利用红外光谱(FTIR)、扫描电镜(SEM)、X-射线衍射(XRD)、热重分析(TGA)等手段对样品的结构进行了表征,并研究了羧甲基纤维素钠样品的黏度性能。     

氨基甲酸酯法再生纤维素膜的结构及性能

利用氨基甲酸酯法制备了再生纤维素膜。采用红外、X射线衍射、扫描电子显微镜等分析方法,对纤维素氨基甲酸酯再生膜（CC再生膜）的性能及结构进行表征。分析了凝固浴浓度和铸膜液浓度分别对CC再生膜的机械性能的影响。结果表明,再生膜为典型的C-II型结晶,结晶度有所降低。CC再生膜表面和断面结构致密、均匀,制备的CC再生膜物理机械性能良好。     

Preparation and properties of chemical cellulose from ascidian tunic and their regenerated cellulose fibers

Chemical cellulose (dissolving pulp) was prepared from ascidian tunic by modified paper‐pulp process (prehydrolysis with acidic aqueous solution of H₂SO₄, digestion with alkali aqueous solution of NaOH/Na₂S, bleaching with aqueous NaOCl solution, and washing with acetone/water). The α‐ cellulose content and the degree of polymerization (DPw) of the chemical cellulose was about 98 wt % and 918, respectively. The Japanese Industrial Standard (JIS) whiteness of the chemical cellulose was about 98%. From the X‐ray diffraction patterns and ¹³C‐NMR spectrum, it was found that the chemical cellulose obtained here has cellulose Iβ crystal structure. A new regenerated cellulose fiber was prepared from the chemical cellulose by dry–wet spinning using N‐methylmorpholine‐ N‐oxide (NMMO)/water (87/13 wt %) as solvent. The new regenerated cellulose fiber prepared in this study has a higher ratio of wet‐to‐dry strength (<0.97) than commercially regenerated cellulose fibers. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1634–1643, 2002.     

Comparison of cellulose and chitin nanocrystals for reinforcing regenerated cellulose fibers

In this study, regenerated cellulose fibers reinforced by cellulose nanocrystals (CENC) and chitin nanocrystals (CHNC) were prepared by blending the nanocrystals suspensions with the cellulose solution in NaOH/urea/water solvent at room temperature. The effect of nanocrystals' addition on the properties of spinning dopes and regenerated fibers were investigated and compared. Results showed that the obtained CENC and CHNC had different dimensions, and both of them increased the viscosity and decreased the transparency of the spinning dopes. However, the dissolution state of cellulose was not changed. CHNC had a greater influence on the properties of spinning dopes, while CENC had more obvious effect on the performance of regenerated fibers. The CENC reinforced fibers showed a higher crystallinity index as compared to the CHNC reinforced fibers. The tensile strength of the regenerated fibers was evidently improved when 3 wt % CENC or 2 wt % CHNC were added, while the elongation at break of the fibers was slightly decreased with the increase of nanocrystals content. The morphology and thermal stability of the regenerated fibers was not affected by the addition of nanocrystals. This study suggested that the dimension, group and content of nanocrystals were important factors for the reinforcement of regenerated cellulose fibers. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44880.     

ZnCl2水溶液制备纤维素膜的研究

以针叶浆为原料,ZnCl2水溶液为溶解溶剂,制备再生纤维素膜。利用单因数实验分析了纤维素膜制各过程中浆浓、反应温度、溶解时间对纤维素膜强度的影响,确定了最佳工艺条件为浆浓3％、反应温度90℃、溶解时间为2h。并通过X-射线衍射（XRD）、傅里叶变换红外光谱（FT-IR）、扫描电镜（SEM）分析,比较经ZnCl2水溶液处理前后纤维的结构和性能变化,发现ZnCl2水溶液是纤维素的非衍生化溶剂,经ZnCl2水溶液处理后的纤维素已由纤维素I转换为纤维素II,制备的再生纤维素膜具有一定的强度,且具有多孔性的特征。     

纤维素/聚氨酯复合气凝胶的制备

以LiOH/尿素（urea） /H2O溶液体系制备的再生纤维素为凝胶骨架,HDI三聚体（N3300）为单体,二月桂酸二丁基锡（DBTDL）为催化剂,原位生成了纤维素/聚氨酯（PU）复合凝胶,再冷冻干燥得到纤维素/PU复合气凝胶.通过红外光谱分析（FT-IR）、X射线衍射（XRD）、扫描电子显微镜（SEM）、N2吸附-脱附、压缩试验对其结构和性能表征.结果表明：纤维素和N3300反应,改变了纤维素的物理和化学结构;N3300浓度增加,与纤维素骨架反应程度增加,复合气凝胶的力学性能增加,SBET和孔隙率减小,密度增加;N3300用量适宜时,可实现复合气凝胶综合性能的平衡.     

离子液体法新型再生纤维素纤维的研究

采用离子液体1-乙基-3-甲基咪唑醋酸盐([EMIM]Ac)为溶剂,制备了纤维素/[EMIM]Ac溶液,研究了该体系的流变性能,利用干喷湿纺的方式制备的新型再生纤维素纤维,并对纤维的结构与性能进行了分析。结果表明,纤维素/[EMIM]Ac溶液为典型的切力变稀流体,在较高剪切速率下,纺丝溶液的黏度变化较小;由该体系制备的新型再生纤维素纤维具有纤维素Ⅱ晶型的结构;随着拉伸比的提高,纤维的取向程度及结晶度增大,纤维力学性能提高。以离子液体为溶剂制备的再生纤维素纤维表面光滑,质地紧密。     

High‐strength regenerated cellulose fibers spun from 1‐butyl‐3‐methylimidazolium chloride solutions

High‐performance regenerated cellulose fibers were prepared from cellulose/1‐butyl‐3‐methylimidazolium chloride (BMIMCl) solutions via dry‐jet wet spinning. The spinnability of the solution was initially evaluated using the maximum winding speed of the solution spinning line under various ambient temperatures and relative humidities in the air gap. The subsequent spinning trials were conducted under various air gap conditions in a water coagulation bath. It was found that low temperature and low relative humidity in the air gap were important to obtain fibers with high tensile strength at a high draw ratio. From a 10 wt % cellulose/BMIMCl solution, regenerated fibers with tensile strength up to 886 MPa were prepared below 22 °C and relative humidity of 50%. High strengthening was also strongly linked with the fixation effect on fibers during washing and drying processes. Furthermore, an effective attempt to prepare higher performance fibers was conducted from a higher polymer concentration solution using a high molecular weight dissolving pulp. Eventually, fibers with a tensile strength of ～1 GPa and Young's modulus over 35 GPa were prepared. These tensile properties were ranked at the highest level for regenerated cellulose fibers prepared by an ionic liquid–based process. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45551.     

Effect of coagulation conditions on fine structure of regenerated cellulosic films made from cellulose/N-methylmorpholine-N-oxide/H2O systems

The important properties of cellulosic fibers in the conditioned state are mainly influenced by fine structure. In particular, the development of new methods of spinning regenerated cellulosic fibers made from a cellulose/N-methylmorpholine-N-oxide (NMMO)/H₂O system require a better understanding of their fine structures in order to explain their special physical properties. The regenerated cellulosic films were made from cellulose/NMMO/H₂O according to the degree of polymerization and solution concentration (wt %) of cellulose and the concentration (wt %) of NMMO in the coagulation bath. The quantification of crystal content was carried out by the resolution of the wide angle X-ray diffraction intensity distribution on the assumption that all diffracted intensities take the form of a symmetrical Gaussian distribution centering at its Bragg angle. The X-ray diffraction patterns resolved into individual integral intensities showed that the polymorphic structure mixed with part cellulose III and II was obtained for only coagulated cellulose films. The degree of crystallinity and apparent crystalline size of regenerated cellulosic films depended on the degree of polymerization, the solution concentration of cellulose, and the concentration of NMMO. The diameter of the microfibril decreased with an increase in the concentration of NMMO. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 2681–2690, 1999